Hydrostatic clamping block



Oct. 12, 1965 J. J. ROSSMAN HYDROSTATIC CLAMPING BLOCK 4 Sheets-Sheet 1 Filed June 8, 1962 INVENTOR. JOSEPH J ROSS/MN BY W},W

ATTORNEY 1965 J. J. ROSSMAN 3,211,445

HYDROSTATI C CLAMPING BLOCK Filed June 8, 1962 4 Sheets-Sheet 3 FEG.

BY W},

ATTORNEY ,so 84 so 87 so Oct. 12, 1965 J. J. ROSSMAN 3,211,445

HYDROSTATIC CLAMPI NG BLOCK Filed June 8, 1962 4 Sheets-Sheet 4 INVENTOR JOSEPH J ROSS/VAN M i/W ATTORNEY United States Patent 3,211,445 HYDROSTATIC CLAMPING BLOCK Joseph I. Rossman, Beech and Kenilworth Aves., Cincinnati, Ohio Filed June 8, 1962, Ser. No. 201,012 2 Claims. (Cl. 269-125) This invention relates to holding devices and it is more particularly concerned with means for securing objects or workpieces in positions to be operated upon by various machine tools.

The use of different machine tools such as planers, millers, lathes, boring mills, etc. requires that the pieces to be worked on be securely held in position while being operated upon. This is frequently difiicult, especially where the workpiece has an irregular surface against which the holding pressure must be applied. Accordingly, the general object of the invention is the provision of means for securely clamping a workpiece to be operated upon in a machine tool irrespective of surface irregularities.

Another object of the invention is the provision of clamping means for the purpose indicated in which the clamping pressures applied to different areas of the workpiece are substantially uniform.

A further object of the invention is the provision of clamping means for the purpose indicated which may be adjusted to accommodate different sizes of workpieces.

A still further object of the invention is the provision of such clamping means which utilize hydrostatically actuated holding members and which include means for adjusting the displacement of the holding members between limits required in any particular operation.

A still further object is the provision of hydrostatic holding means as an integral part of an arbor or other conventional holding unit of a machine tool.

These and still further objects, advantages and features of the invention will appear more fully from the following description considered together with the accompanying drawing.

In the drawing:

FIG. 1 is a fragmentary top plan view of a conventional milling machine showing an embodiment of the invention associated with the holding unit in respect to a workpiece to be operated upon.

FIG. 2 is a sectional view along the line 2-2 of FIG. 1.

FIG. 3 is a side elevational view of the embodiment apart from the machine tool.

FIG. 4 is an end elevational view from the right side of FIG. 3.

FIG. 5 is a longitudinal sectional view along the line 55 of FIG. 3 in association with a fragmentary portion of the workpiece.

FIG. 6 is a sectional view along the line 6-6 of FIG. 5.

FIG. 7 is a cross sectional view along the line 7-7 of FIG. 3 in association with a fragmentary portion of the workpiece.

FIG. 8 is a sectional view of a fragmentary portion of the embodiment along the line 8-8 of FIG. 3 on a larger scale.

FIG. 9 is a sectional view along the line 9-9 of FIG. 6 on a larger scale.

FIG. 10 is a top plan view of an arbor comprising a second embodiment of the invention in conjunction with a tubular workpiece, said embodiment and workpiece being partly broken away.

FIG. 11 is a cross sectional view along the line 11-11 of FIG. 10.

FIG. 12 is a longitudinal sectional view along the line 12-12 of FIG. 11 partly broken away and with the workpiece removed.

FIG. 13 is a view similar to FIG. 12 with the plunger moved to its innermost position from its outermost position of FIG. 12.

.FIGS. 14, 15 and 16 are cross sectional views along the lines 1414, 15--15 and 1616, respectively, of FIG. 12.

FIG. 17 is a transverse sectional view along the line 1717 of FIG. 10.

FIG. 18 is a sectional view along the line 18-18 of FIG. 16 on an enlarged scale.

Referring with more particularly to the drawing the embodiment of FIGS. 1 to 9 is illustrated in conjunction with a conventional machine tool such as a milling machine 21 having clamping jaws consisting of a fixed jaw 22 and a movable jaw 23 actuated by a lead screw 24 having a hand wheel 25.

By way of example, a workpiece 26 to be operated upon by the machine 21 has an irregular surface 27' against which clamping pressure is to be applied. It is disposed between the jaws 22 and 23 and the embodiment of the invention comprises a block 28 having pressure pins 29 projecting therefrom. The block is disposed between the irregular surface 27 and one of the jaws, say the jaw 23, with the pins abutting the irregular surface 27.

The pins 29 are slidably mounted on the block. Each pin has a root piston 30 slidably disposed in a cylindrical:

recess or Well 31 of the block. The upper end of the well 31 has an enlarged threaded section 32 to engage the threads 33 of an inset cylindrical collar bearing 34v which slidably engages the pin 29 and supports it against lateral displacement. The upper edge of the collar hearing 34 is provided with slots 35 or other configuration for engaging a screw driver or other tool to be used for inserting and removing it as may be necessary. The upwardly facing shoulder 36 formed by the enlargement of the section 32 acts as an abutment. for the lower end of the bearing 34 while the bearing itself acts as an abutment for the piston 30 to limit its upward displacement in the well 31. Sealing rings 36 are provided in an annular recess 37 of the piston.

In the embodiment illustrated there are provided two. longitudinal rows of such pins 29 and wells 31 but any number of such rows or any arrangement of such pins and wells other than linear rows may be used depending upon the need therefor and the configuration of the particular workpiece to be held thereby. The wells 31 are, all connected together by a system of channels. In the embodiment illustrated, each row has an elongated channel 38 and 39, respectively, communicating with the bottom of the wells thereof. The channels 38 and 39 communicate with each other by a cross channel 40 which cross channel extends to and is further connected to one end of a cylindrical hydraulic reservoir 41, the other end of the reservoir 41 extending to the exterior of the block.

The channels 38, 39 and 40 and the reservoir 41 together with portions of the wells 31 below the piston 30 are filled with a hydraulic fluid, such as oil.

The reservoir 41 is provided with a piston 43 from which a piston rod 44 integral therewith extends to an enlarged threaded end portion 45 of the reservoir. The opposite end of the piston rod 44 is integral with a head 46 which is threadedly engaged with enlarged portion 45. The outer end of the head 46 has a center depression 47 of a shape to fit a turning tool such as a conventional Allen wrench. By these means the average distance which the pins 29 project beyond the block can be changed by turning the head 46 to move the corresponding piston 43 inward or outward as may be desired or necessary in any particular case. Such an adjustment may be necessary in many different instances such as to tighten or loosen a workpiece without disturbing the setting of the jaws of the machine tool; also, to take up the slack caused by leakage of fluid in the hydrostatic system. It also permits, in special cases to clamp a workpiece between two fixed jaws or holding members or where duplicate machining operations are to be performed on successive and identical workpiece units and in view of which precision setting of the workpiece is necessary.

The embodiment illustrated in FIGS. to 18 comprises a generally cylindrical block 50 having a mounting flange 51 provided with openings such as the peripheral slots 52 for engaging mounting bolts (not shown) to secure the device to the machine tool on which it is to be used.

The block 50 comprises two removable jaw sections 53 and 54 one disposed diagonally downward on one side and the other disposed diagonally downward on the opposite side. These jaw sections have outwardly projecting clamping teeth 55 and 56 and they are held in position by means of bolts 57 and 58, respectively.

At the top of the block 50 a group of cylindrical wells are provided such as the longitudinal row of wells 59. These wells are similar to the wells 31 of the previously described embodiment and they are provided with pins 60, pistons 61 and collar bearings 62 similar to the pins 29, pistons 30 and collar bearings 34, respectively, of the previous embodiment.

The bottoms of the wells 59 communicate With a longitudinal channel 63 in the block 50. The channel 63 has an enlarged portion 64 at the arbor end in which a master piston 65 is reciprocatingly disposed. A screw plug 66 is disposed in the outer end of the enlarged portion 64 and a piston rod 67 integral with the piston 65 extends through a central bore 68 of the plug. The opposite end of the piston rod 67 is integral with a piston 69 of an air motor 70, the cylinder housing 71 of which is secured to the block 50 by means of bolts 72 passing through a flange 73 of the housing.

The piston 65 is biased to its outermost position by means of a coil spring 74 disposed in the enlarged portion 64 between the piston and the outwardly facing shoulder 75 resulting from the enlargement of the portion 64.

A hydraulic reservoir is also provided in this second embodiment similar to that of the previous embodiment and it comprises a longitudinal cylindrical bore 76 that communicates with the channel 63 such as by a cross duct 77. A piston 78 is reciprocatingly disposed in the bore 76 and is integral with a piston rod 79 which extends outwardly to an enlarged threaded section 80 of the bore 76 where it is secured to a plug 81 threadedly engaged with the section 80. The plug 81 is provided with a screw driver slot 82 or other conventional tool engaging means for turning it.

The pins 60 are provided with plates or shoes 83 having clamping teeth 84 on their outer sides to engage the workpiece and recesses 85 on the inner side to engage the outer ends of the pins 60. Each of the shoes are preferably provided for bridging a pair of adjacent pins and they are held in contact with these pins by means of expansible split resilient rings 86 transversely encircling the block 50 and disposed in slots 87 recessed in the shoes and slots 88 and 89 in the fixed jaw sections 53 and 54, respectively.

By these means a workpiece, such as a tubular member 90, may be readily clamped to the arbor by placing it over the block 50 and actuating the air motor 70 by opening the valve 91 leading from a source of air pressure. This causes the air piston 69 to move inwardly and to move the hydraulic piston 65 inwardly against the coil spring 74. The resulting pressure developed in the hydrostatic system urges the pins outwardly and forces the shoes 83- in conjunction with the fixed jaws 53 and 54 to clamp the workpiece in position. When the tooling operation has been completed on the workpiece, the air pressure in the motor 70 is released by means of the valve 91 thereby permitting the spring 74 to move the piston outward. This releases the hydrostatic pressure against the pin pistons 61 and results in their being retracted under the force of the resilient rings 86 acting against the shoes 83.

Having thus described my invention, I claim:

1. A machine tool workpiece clamp comprising a cylindrical block, a plurality of pins set therein movable from retracted to protracted positions under hydrostatic pressure of a confined liquid, fixed jaw members carried by the block in circumferentially spaced relation to said pins, means removably securing said jaw members to the block, workpiece engaging shoes carried by said pins, resilient members encircling said block in contact with said shoes for holding them against their respective pins and for urging the pins and shoes to retracted positions.

2. A machine tool workpiece clamp comprising a cylindrical block, a plurality of pins set therein movable from retracted to protracted positions under hydrostatic pressure of a confined liquid, fixed jaw members carried by the block in circumferentially spaced relation to said pins, means removably securing said jaw members to the block, workpiece engaging shoes carried by said pins, each shoe being supported by a pair of consecutive pins, resilient members encircling said block in contact with said shoes for holding them against their respective pins and urging the pins and shoes to retracted positions.

References Cited by the Examiner UNITED STATES PATENTS 1,421,208 6/22 Gauldie 308-l60 1,430,226 9/22 Goodreau 26927 1,453,176 4/23 Perrine 269266 2,692,633 10/54 Green 269267 X 2,829,566 4/56 Gecks et al. 26920 X 2,963,298 12/60 Better et al. 82-44 X FOREIGN PATENTS 1,254,117 1/61 France.

ROBERT C. RIORDON, Primary Examiner. 

1. A MACHINE TOOL WORKPIECE CLAMP COMPRISING A CYLINDRICAL BLOCK, A PLURALITY OF PINS SET THEREIN MOVABLE FROM RETRACTED TO PROTRACTED POSITIONS UNDER HYDROSTATIC PRESSURE OF A CONFINED LIQUID, FIXED JAW MEMBERS CARRIED BY THE BLOCK IN CIRCUMFERENTIALLY SPACED RELATION TO SAID PINS, MEANS REMOVABLY SECURING SAID JAW MEMBERS TO THE BLOCK, 